Rigid cellular plastics, such as expanded polystyrene (EPS), expanded polypropylene (EPP), and expanded polylactic acid (EPLA) exhibit a variety of useful properties that have numerous uses within society. Due to their durable and lightweight properties, such materials are particularly useful as packaging and containers to contain, transport and/or store a variety of goods. In this regard, EPS has also been used in the building construction industry as void forming pods in building foundations, as well as a variety of other uses, across various industries.
In packaging applications, cardboard boxes have traditionally proven to be a popular form of packaging due to a variety of reasons. Cardboard can be created relatively cheaply and can be simply formed into blanks that are able to be partially assembled for storage and transported in a flat form that can be simply folded to form a box as desired. Cardboard boxes can be made to a variety of sizes and can be reinforced as required through the use of tape or stables to withstand some force. However, due to the nature of cardboard, it has limited durability and can be particularly susceptible to failure when exposed to liquids, impact and other types of treatment which can cause the cardboard boxes to fail and lose structural integrity.
With the continually widespread acceptance of rigid cellular plastics, such as EPS, EPP and EPLA, the ability to utilise these materials and their inherent superior properties to provide a more durable and useful container and packaging solutions, has only recently been realised. Such rigid cellular plastics have a particular application for the storage and transport of perishable materials, such as agricultural and horticultural products, as they are largely impermeable. As a result, they provide an environment for storing items which can be temperature regulated and retained in a gas-tight or water-tight state. Due to the nature of such materials, boxes formed from EPS, EPP and EPLA also have a degree of shock and impact resistance which provides protection to the materials stored or carried therein.
However, despite the various benefits that such rigid cellular plastics offer for use in packaging purposes, due to the manner in which the materials are formed, they introduce a number of problems in their usage that have traditionally offset these advantages. As the formation of a box or similar packaging requires controlled expansion of the material within a mould, most boxes or packaging formed from such materials are formed to assume a specific three-dimensional shape, as a single piece. Whilst this is useful and enables the formation of a dimensionally accurate final product, the resultant three-dimensional product occupies a predetermined volume even when empty, thereby requiring space to store the product when not in use. This results in a product that takes up a significant space, which makes such products less economic to store and transport when empty. Thus after use, it is common for such EPS boxes to be broken down and disposed of by being placed in land-fill and not being reused, despite their potential for such re-use.
A variety of systems have been proposed for making EPS boxes in a flat, blank form that can be assembling into a box for use. Such systems generally achieve this through the formation of hinges or fold regions in the blank during the moulding process and/or by applying a compression force to the blank following formation to form a hinge at a predetermined location. Unfortunately, inherent in using such a conventional means for achieving such a fold region or hinge generally requires creating a region of weakness in the blank about which the planar regions of the blank on either sides of the weakness are able to be folded with respect to each other. Whilst such a system may provide a means for folding a planar piece of material into a box or the like, the direct result of creating an area of weakness in the blank to form the hinge is that it enhances the likelihood of the product to fail during use at the hinge region, thereby significantly compromising the integrity of the product and the contents stored therein.
One system and method for addressing this problem is described in more detail in the Applicant's International PCT Patent Application No. PCT/AU2010/000340. The system and method described therein employs a two-step process for achieving the fold region or hinge in the blank, with the first step comprising the moulding of the blank to form the overall shape of the hinge or fold region and the second step requiring removal of the moulded blank and further compressing the hinge or fold region so as to provide a strengthened hinge or fold region having compressed material located therein.
Whilst the Applicant's above described system and method has proven effective in enabling boxes to be assembled from a flat EPS blank, such a two-step process requires dedicated machinery and processes to replicate. Therefore, there is a need to provide an improved process for creating a hinge or fold region in a planar piece of rigid cellular plastic material that enhances the strength of the material in the hinge or fold region and which reduces the need to provide separate tooling and steps during the formation process.
The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.